/******************************************************
The B-tree

(c) 1994-1996 Innobase Oy

Created 6/2/1994 Heikki Tuuri
*******************************************************/

#include "btr0btr.h"

#ifdef UNIV_NONINL
#include "btr0btr.ic"
#endif

#include "fsp0fsp.h"
#include "page0page.h"
#include "btr0cur.h"
#include "btr0sea.h"
#include "btr0pcur.h"
#include "rem0cmp.h"
#include "lock0lock.h"
#include "ibuf0ibuf.h"
#include "trx0trx.h"

/*
Latching strategy of the InnoDB B-tree
--------------------------------------
A tree latch protects all non-leaf nodes of the tree. Each node of a tree
also has a latch of its own.

A B-tree operation normally first acquires an S-latch on the tree. It
searches down the tree and releases the tree latch when it has the
leaf node latch. To save CPU time we do not acquire any latch on
non-leaf nodes of the tree during a search, those pages are only bufferfixed.

If an operation needs to restructure the tree, it acquires an X-latch on
the tree before searching to a leaf node. If it needs, for example, to
split a leaf,
(1) InnoDB decides the split point in the leaf,
(2) allocates a new page,
(3) inserts the appropriate node pointer to the first non-leaf level,
(4) releases the tree X-latch,
(5) and then moves records from the leaf to the new allocated page.

Node pointers
-------------
Leaf pages of a B-tree contain the index records stored in the
tree. On levels n > 0 we store 'node pointers' to pages on level
n - 1. For each page there is exactly one node pointer stored:
thus the our tree is an ordinary B-tree, not a B-link tree.

A node pointer contains a prefix P of an index record. The prefix
is long enough so that it determines an index record uniquely.
The file page number of the child page is added as the last
field. To the child page we can store node pointers or index records
which are >= P in the alphabetical order, but < P1 if there is
a next node pointer on the level, and P1 is its prefix.

If a node pointer with a prefix P points to a non-leaf child,
then the leftmost record in the child must have the same
prefix P. If it points to a leaf node, the child is not required
to contain any record with a prefix equal to P. The leaf case
is decided this way to allow arbitrary deletions in a leaf node
without touching upper levels of the tree.

We have predefined a special minimum record which we
define as the smallest record in any alphabetical order.
A minimum record is denoted by setting a bit in the record
header. A minimum record acts as the prefix of a node pointer
which points to a leftmost node on any level of the tree.

File page allocation
--------------------
In the root node of a B-tree there are two file segment headers.
The leaf pages of a tree are allocated from one file segment, to
make them consecutive on disk if possible. From the other file segment
we allocate pages for the non-leaf levels of the tree.
*/

/******************************************************************
Creates a new index page to the tree (not the root, and also not
used in page reorganization). */
static void btr_page_create(
    /*============*/
    page_t *page,      /* in: page to be created */
    dict_tree_t *tree, /* in: index tree */
    mtr_t *mtr);       /* in: mtr */
/****************************************************************
Returns the upper level node pointer to a page. It is assumed that
mtr holds an x-latch on the tree. */
static rec_t *btr_page_get_father_node_ptr(
    /*=========================*/
    /* out: pointer to node pointer record */
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page: must contain at least one
                       user record */
    mtr_t *mtr);       /* in: mtr */
/*****************************************************************
Empties an index page. */
static void btr_page_empty(
    /*===========*/
    page_t *page, /* in: page to be emptied */
    mtr_t *mtr);  /* in: mtr */
/*****************************************************************
Returns TRUE if the insert fits on the appropriate half-page
with the chosen split_rec. */
static ibool btr_page_insert_fits(
    /*=================*/
    /* out: TRUE if fits */
    btr_cur_t *cursor,    /* in: cursor at which insert
                          should be made */
    rec_t *split_rec,     /* in: suggestion for first record
                          on upper half-page, or NULL if
                          tuple should be first */
    const ulint *offsets, /* in: rec_get_offsets(
                          split_rec, cursor->index) */
    dtuple_t *tuple,      /* in: tuple to insert */
    mem_heap_t *heap);    /* in: temporary memory heap */

/******************************************************************
Gets the root node of a tree and x-latches it. */

page_t *btr_root_get(
    /*=========*/
    /* out: root page, x-latched */
    dict_tree_t *tree, /* in: index tree */
    mtr_t *mtr)        /* in: mtr */
{
  ulint space;
  ulint root_page_no;
  page_t *root;

  space = dict_tree_get_space(tree);
  root_page_no = dict_tree_get_page(tree);

  root = btr_page_get(space, root_page_no, RW_X_LATCH, mtr);
  ut_a((ibool) !!page_is_comp(root) == UT_LIST_GET_FIRST(tree->tree_indexes)->table->comp);

  return (root);
}

/*****************************************************************
Gets pointer to the previous user record in the tree. It is assumed that
the caller has appropriate latches on the page and its neighbor. */

rec_t *btr_get_prev_user_rec(
    /*==================*/
    /* out: previous user record, NULL if there is none */
    rec_t *rec, /* in: record on leaf level */
    mtr_t *mtr) /* in: mtr holding a latch on the page, and if
                needed, also to the previous page */
{
  page_t *page;
  page_t *prev_page;
  ulint prev_page_no;
  ulint space;

  if (!page_rec_is_infimum(rec))
  {
    rec_t *prev_rec = page_rec_get_prev(rec);

    if (!page_rec_is_infimum(prev_rec))
    {
      return (prev_rec);
    }
  }

  page = buf_frame_align(rec);
  prev_page_no = btr_page_get_prev(page, mtr);
  space = buf_frame_get_space_id(page);

  if (prev_page_no != FIL_NULL)
  {
    prev_page = buf_page_get_with_no_latch(space, prev_page_no, mtr);
    /* The caller must already have a latch to the brother */
    ut_ad((mtr_memo_contains(mtr, buf_block_align(prev_page), MTR_MEMO_PAGE_S_FIX)) ||
          (mtr_memo_contains(mtr, buf_block_align(prev_page), MTR_MEMO_PAGE_X_FIX)));
    ut_a(page_is_comp(prev_page) == page_is_comp(page));

    return (page_rec_get_prev(page_get_supremum_rec(prev_page)));
  }

  return (NULL);
}

/*****************************************************************
Gets pointer to the next user record in the tree. It is assumed that the
caller has appropriate latches on the page and its neighbor. */

rec_t *btr_get_next_user_rec(
    /*==================*/
    /* out: next user record, NULL if there is none */
    rec_t *rec, /* in: record on leaf level */
    mtr_t *mtr) /* in: mtr holding a latch on the page, and if
                needed, also to the next page */
{
  page_t *page;
  page_t *next_page;
  ulint next_page_no;
  ulint space;

  if (!page_rec_is_supremum(rec))
  {
    rec_t *next_rec = page_rec_get_next(rec);

    if (!page_rec_is_supremum(next_rec))
    {
      return (next_rec);
    }
  }

  page = buf_frame_align(rec);
  next_page_no = btr_page_get_next(page, mtr);
  space = buf_frame_get_space_id(page);

  if (next_page_no != FIL_NULL)
  {
    next_page = buf_page_get_with_no_latch(space, next_page_no, mtr);
    /* The caller must already have a latch to the brother */
    ut_ad((mtr_memo_contains(mtr, buf_block_align(next_page), MTR_MEMO_PAGE_S_FIX)) ||
          (mtr_memo_contains(mtr, buf_block_align(next_page), MTR_MEMO_PAGE_X_FIX)));

    ut_a(page_is_comp(next_page) == page_is_comp(page));
    return (page_rec_get_next(page_get_infimum_rec(next_page)));
  }

  return (NULL);
}

/******************************************************************
Creates a new index page to the tree (not the root, and also not used in
page reorganization). */
static void btr_page_create(
    /*============*/
    page_t *page,      /* in: page to be created */
    dict_tree_t *tree, /* in: index tree */
    mtr_t *mtr)        /* in: mtr */
{
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  page_create(page, mtr, UT_LIST_GET_FIRST(tree->tree_indexes)->table->comp);
  buf_block_align(page)->check_index_page_at_flush = TRUE;

  btr_page_set_index_id(page, tree->id, mtr);
}

/******************************************************************
Allocates a new file page to be used in an ibuf tree. Takes the page from
the free list of the tree, which must contain pages! */
static page_t *btr_page_alloc_for_ibuf(
    /*====================*/
    /* out: new allocated page, x-latched */
    dict_tree_t *tree, /* in: index tree */
    mtr_t *mtr)        /* in: mtr */
{
  fil_addr_t node_addr;
  page_t *root;
  page_t *new_page;

  root = btr_root_get(tree, mtr);

  node_addr = flst_get_first(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, mtr);
  ut_a(node_addr.page != FIL_NULL);

  new_page = buf_page_get(dict_tree_get_space(tree), node_addr.page, RW_X_LATCH, mtr);
#ifdef UNIV_SYNC_DEBUG
  buf_page_dbg_add_level(new_page, SYNC_TREE_NODE_NEW);
#endif /* UNIV_SYNC_DEBUG */

  flst_remove(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, new_page + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST_NODE, mtr);
  ut_ad(flst_validate(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, mtr));

  return (new_page);
}

/******************************************************************
Allocates a new file page to be used in an index tree. NOTE: we assume
that the caller has made the reservation for free extents! */

page_t *btr_page_alloc(
    /*===========*/
    /* out: new allocated page, x-latched;
    NULL if out of space */
    dict_tree_t *tree,   /* in: index tree */
    ulint hint_page_no,  /* in: hint of a good page */
    byte file_direction, /* in: direction where a possible
                         page split is made */
    ulint level,         /* in: level where the page is placed
                         in the tree */
    mtr_t *mtr)          /* in: mtr */
{
  fseg_header_t *seg_header;
  page_t *root;
  page_t *new_page;
  ulint new_page_no;

  if (tree->type & DICT_IBUF)
  {
    return (btr_page_alloc_for_ibuf(tree, mtr));
  }

  root = btr_root_get(tree, mtr);

  if (level == 0)
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_LEAF;
  }
  else
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_TOP;
  }

  /* Parameter TRUE below states that the caller has made the
  reservation for free extents, and thus we know that a page can
  be allocated: */

  new_page_no = fseg_alloc_free_page_general(seg_header, hint_page_no, file_direction, TRUE, mtr);
  if (new_page_no == FIL_NULL)
  {
    return (NULL);
  }

  new_page = buf_page_get(dict_tree_get_space(tree), new_page_no, RW_X_LATCH, mtr);
#ifdef UNIV_SYNC_DEBUG
  buf_page_dbg_add_level(new_page, SYNC_TREE_NODE_NEW);
#endif /* UNIV_SYNC_DEBUG */

  return (new_page);
}

/******************************************************************
Gets the number of pages in a B-tree. */

ulint btr_get_size(
    /*=========*/
    /* out: number of pages */
    dict_index_t *index, /* in: index */
    ulint flag)          /* in: BTR_N_LEAF_PAGES or BTR_TOTAL_SIZE */
{
  fseg_header_t *seg_header;
  page_t *root;
  ulint n;
  ulint dummy;
  mtr_t mtr;

  mtr_start(&mtr);

  mtr_s_lock(dict_tree_get_lock(index->tree), &mtr);

  root = btr_root_get(index->tree, &mtr);

  if (flag == BTR_N_LEAF_PAGES)
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_LEAF;

    fseg_n_reserved_pages(seg_header, &n, &mtr);
  }
  else if (flag == BTR_TOTAL_SIZE)
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_TOP;

    n = fseg_n_reserved_pages(seg_header, &dummy, &mtr);

    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_LEAF;

    n += fseg_n_reserved_pages(seg_header, &dummy, &mtr);
  }
  else
  {
    ut_error;
  }

  mtr_commit(&mtr);

  return (n);
}

/******************************************************************
Frees a page used in an ibuf tree. Puts the page to the free list of the
ibuf tree. */
static void btr_page_free_for_ibuf(
    /*===================*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page to be freed, x-latched */
    mtr_t *mtr)        /* in: mtr */
{
  page_t *root;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  root = btr_root_get(tree, mtr);

  flst_add_first(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, page + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST_NODE, mtr);

  ut_ad(flst_validate(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, mtr));
}

/******************************************************************
Frees a file page used in an index tree. Can be used also to (BLOB)
external storage pages, because the page level 0 can be given as an
argument. */

void btr_page_free_low(
    /*==============*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page to be freed, x-latched */
    ulint level,       /* in: page level */
    mtr_t *mtr)        /* in: mtr */
{
  fseg_header_t *seg_header;
  page_t *root;
  ulint space;
  ulint page_no;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  /* The page gets invalid for optimistic searches: increment the frame
  modify clock */

  buf_frame_modify_clock_inc(page);

  if (tree->type & DICT_IBUF)
  {
    btr_page_free_for_ibuf(tree, page, mtr);

    return;
  }

  root = btr_root_get(tree, mtr);

  if (level == 0)
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_LEAF;
  }
  else
  {
    seg_header = root + PAGE_HEADER + PAGE_BTR_SEG_TOP;
  }

  space = buf_frame_get_space_id(page);
  page_no = buf_frame_get_page_no(page);

  fseg_free_page(seg_header, space, page_no, mtr);
}

/******************************************************************
Frees a file page used in an index tree. NOTE: cannot free field external
storage pages because the page must contain info on its level. */

void btr_page_free(
    /*==========*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page to be freed, x-latched */
    mtr_t *mtr)        /* in: mtr */
{
  ulint level;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  level = btr_page_get_level(page, mtr);

  btr_page_free_low(tree, page, level, mtr);
}

/******************************************************************
Sets the child node file address in a node pointer. */
UNIV_INLINE
void btr_node_ptr_set_child_page_no(
    /*===========================*/
    rec_t *rec,           /* in: node pointer record */
    const ulint *offsets, /* in: array returned by rec_get_offsets() */
    ulint page_no,        /* in: child node address */
    mtr_t *mtr)           /* in: mtr */
{
  byte *field;
  ulint len;

  ut_ad(rec_offs_validate(rec, NULL, offsets));
  ut_ad(0 < btr_page_get_level(buf_frame_align(rec), mtr));
  ut_ad(!rec_offs_comp(offsets) || rec_get_node_ptr_flag(rec));

  /* The child address is in the last field */
  field = rec_get_nth_field(rec, offsets, rec_offs_n_fields(offsets) - 1, &len);

  ut_ad(len == 4);

  mlog_write_ulint(field, page_no, MLOG_4BYTES, mtr);
}

/****************************************************************
Returns the child page of a node pointer and x-latches it. */
static page_t *btr_node_ptr_get_child(
    /*===================*/
    /* out: child page, x-latched */
    rec_t *node_ptr,      /* in: node pointer */
    const ulint *offsets, /* in: array returned by rec_get_offsets() */
    mtr_t *mtr)           /* in: mtr */
{
  ulint page_no;
  ulint space;
  page_t *page;

  ut_ad(rec_offs_validate(node_ptr, NULL, offsets));
  space = buf_frame_get_space_id(node_ptr);
  page_no = btr_node_ptr_get_child_page_no(node_ptr, offsets);

  page = btr_page_get(space, page_no, RW_X_LATCH, mtr);

  return (page);
}

/****************************************************************
Returns the upper level node pointer to a page. It is assumed that mtr holds
an x-latch on the tree. */
static rec_t *btr_page_get_father_for_rec(
    /*========================*/
    /* out: pointer to node pointer record,
    its page x-latched */
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page: must contain at least one
                       user record */
    rec_t *user_rec,   /* in: user_record on page */
    mtr_t *mtr)        /* in: mtr */
{
  mem_heap_t *heap;
  dtuple_t *tuple;
  btr_cur_t cursor;
  rec_t *node_ptr;
  dict_index_t *index;
  ulint offsets_[REC_OFFS_NORMAL_SIZE];
  ulint *offsets = offsets_;
  *offsets_ = (sizeof offsets_) / sizeof *offsets_;

  ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
  ut_a(page_rec_is_user_rec(user_rec));

  ut_ad(dict_tree_get_page(tree) != buf_frame_get_page_no(page));

  heap = mem_heap_create(100);

  tuple = dict_tree_build_node_ptr(tree, user_rec, 0, heap, btr_page_get_level(page, mtr));
  index = UT_LIST_GET_FIRST(tree->tree_indexes);

  /* In the following, we choose just any index from the tree as the
  first parameter for btr_cur_search_to_nth_level. */

  btr_cur_search_to_nth_level(index, btr_page_get_level(page, mtr) + 1, tuple, PAGE_CUR_LE, BTR_CONT_MODIFY_TREE,
                              &cursor, 0, mtr);

  node_ptr = btr_cur_get_rec(&cursor);
  offsets = rec_get_offsets(node_ptr, index, offsets, ULINT_UNDEFINED, &heap);

  if (btr_node_ptr_get_child_page_no(node_ptr, offsets) != buf_frame_get_page_no(page))
  {
    rec_t *print_rec;
    fputs("InnoDB: Dump of the child page:\n", stderr);
    buf_page_print(buf_frame_align(page));
    fputs("InnoDB: Dump of the parent page:\n", stderr);
    buf_page_print(buf_frame_align(node_ptr));

    fputs("InnoDB: Corruption of an index tree: table ", stderr);
    ut_print_name(stderr, NULL, index->table_name);
    fputs(", index ", stderr);
    ut_print_name(stderr, NULL, index->name);
    fprintf(stderr,
            ",\n"
            "InnoDB: father ptr page no %lu, child page no %lu\n",
            (ulong)btr_node_ptr_get_child_page_no(node_ptr, offsets), (ulong)buf_frame_get_page_no(page));
    print_rec = page_rec_get_next(page_get_infimum_rec(page));
    offsets = rec_get_offsets(print_rec, index, offsets, ULINT_UNDEFINED, &heap);
    page_rec_print(print_rec, offsets);
    offsets = rec_get_offsets(node_ptr, index, offsets, ULINT_UNDEFINED, &heap);
    page_rec_print(node_ptr, offsets);

    fputs(
        "InnoDB: You should dump + drop + reimport the table to fix the\n"
        "InnoDB: corruption. If the crash happens at the database startup, see\n"
        "InnoDB: http://dev.mysql.com/doc/mysql/en/Forcing_recovery.html about\n"
        "InnoDB: forcing recovery. Then dump + drop + reimport.\n",
        stderr);
  }

  ut_a(btr_node_ptr_get_child_page_no(node_ptr, offsets) == buf_frame_get_page_no(page));
  mem_heap_free(heap);

  return (node_ptr);
}

/****************************************************************
Returns the upper level node pointer to a page. It is assumed that
mtr holds an x-latch on the tree. */
static rec_t *btr_page_get_father_node_ptr(
    /*=========================*/
    /* out: pointer to node pointer record */
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page: must contain at least one
                       user record */
    mtr_t *mtr)        /* in: mtr */
{
  return (btr_page_get_father_for_rec(tree, page, page_rec_get_next(page_get_infimum_rec(page)), mtr));
}

/****************************************************************
Creates the root node for a new index tree. */

ulint btr_create(
    /*=======*/
    /* out: page number of the created root, FIL_NULL if
    did not succeed */
    ulint type,      /* in: type of the index */
    ulint space,     /* in: space where created */
    dulint index_id, /* in: index id */
    ulint comp,      /* in: nonzero=compact page format */
    mtr_t *mtr)      /* in: mini-transaction handle */
{
  ulint page_no;
  buf_frame_t *ibuf_hdr_frame;
  buf_frame_t *frame;
  page_t *page;

  /* Create the two new segments (one, in the case of an ibuf tree) for
  the index tree; the segment headers are put on the allocated root page
  (for an ibuf tree, not in the root, but on a separate ibuf header
  page) */

  if (type & DICT_IBUF)
  {
    /* Allocate first the ibuf header page */
    ibuf_hdr_frame = fseg_create(space, 0, IBUF_HEADER + IBUF_TREE_SEG_HEADER, mtr);

#ifdef UNIV_SYNC_DEBUG
    buf_page_dbg_add_level(ibuf_hdr_frame, SYNC_TREE_NODE_NEW);
#endif /* UNIV_SYNC_DEBUG */
    ut_ad(buf_frame_get_page_no(ibuf_hdr_frame) == IBUF_HEADER_PAGE_NO);
    /* Allocate then the next page to the segment: it will be the
    tree root page */

    page_no =
        fseg_alloc_free_page(ibuf_hdr_frame + IBUF_HEADER + IBUF_TREE_SEG_HEADER, IBUF_TREE_ROOT_PAGE_NO, FSP_UP, mtr);
    ut_ad(page_no == IBUF_TREE_ROOT_PAGE_NO);

    frame = buf_page_get(space, page_no, RW_X_LATCH, mtr);
  }
  else
  {
    frame = fseg_create(space, 0, PAGE_HEADER + PAGE_BTR_SEG_TOP, mtr);
  }

  if (frame == NULL)
  {
    return (FIL_NULL);
  }

  page_no = buf_frame_get_page_no(frame);

#ifdef UNIV_SYNC_DEBUG
  buf_page_dbg_add_level(frame, SYNC_TREE_NODE_NEW);
#endif /* UNIV_SYNC_DEBUG */

  if (type & DICT_IBUF)
  {
    /* It is an insert buffer tree: initialize the free list */

    ut_ad(page_no == IBUF_TREE_ROOT_PAGE_NO);

    flst_init(frame + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, mtr);
  }
  else
  {
    /* It is a non-ibuf tree: create a file segment for leaf
    pages */
    fseg_create(space, page_no, PAGE_HEADER + PAGE_BTR_SEG_LEAF, mtr);
    /* The fseg create acquires a second latch on the page,
    therefore we must declare it: */
#ifdef UNIV_SYNC_DEBUG
    buf_page_dbg_add_level(frame, SYNC_TREE_NODE_NEW);
#endif /* UNIV_SYNC_DEBUG */
  }

  /* Create a new index page on the the allocated segment page */
  page = page_create(frame, mtr, comp);
  buf_block_align(page)->check_index_page_at_flush = TRUE;

  /* Set the index id of the page */
  btr_page_set_index_id(page, index_id, mtr);

  /* Set the level of the new index page */
  btr_page_set_level(page, 0, mtr);

  /* Set the next node and previous node fields */
  btr_page_set_next(page, FIL_NULL, mtr);
  btr_page_set_prev(page, FIL_NULL, mtr);

  /* We reset the free bits for the page to allow creation of several
  trees in the same mtr, otherwise the latch on a bitmap page would
  prevent it because of the latching order */

  ibuf_reset_free_bits_with_type(type, page);

  /* In the following assertion we test that two records of maximum
  allowed size fit on the root page: this fact is needed to ensure
  correctness of split algorithms */

  ut_ad(page_get_max_insert_size(page, 2) > 2 * BTR_PAGE_MAX_REC_SIZE);

  return (page_no);
}

/****************************************************************
Frees a B-tree except the root page, which MUST be freed after this
by calling btr_free_root. */

void btr_free_but_not_root(
    /*==================*/
    ulint space,        /* in: space where created */
    ulint root_page_no) /* in: root page number */
{
  ibool finished;
  page_t *root;
  mtr_t mtr;

leaf_loop:
  mtr_start(&mtr);

  root = btr_page_get(space, root_page_no, RW_X_LATCH, &mtr);

  /* NOTE: page hash indexes are dropped when a page is freed inside
  fsp0fsp. */

  finished = fseg_free_step(root + PAGE_HEADER + PAGE_BTR_SEG_LEAF, &mtr);
  mtr_commit(&mtr);

  if (!finished)
  {
    goto leaf_loop;
  }
top_loop:
  mtr_start(&mtr);

  root = btr_page_get(space, root_page_no, RW_X_LATCH, &mtr);

  finished = fseg_free_step_not_header(root + PAGE_HEADER + PAGE_BTR_SEG_TOP, &mtr);
  mtr_commit(&mtr);

  if (!finished)
  {
    goto top_loop;
  }
}

/****************************************************************
Frees the B-tree root page. Other tree MUST already have been freed. */

void btr_free_root(
    /*==========*/
    ulint space,        /* in: space where created */
    ulint root_page_no, /* in: root page number */
    mtr_t *mtr)         /* in: a mini-transaction which has already
                        been started */
{
  ibool finished;
  page_t *root;

  root = btr_page_get(space, root_page_no, RW_X_LATCH, mtr);

  btr_search_drop_page_hash_index(root);
top_loop:
  finished = fseg_free_step(root + PAGE_HEADER + PAGE_BTR_SEG_TOP, mtr);
  if (!finished)
  {
    goto top_loop;
  }
}

/*****************************************************************
Reorganizes an index page. */
static void btr_page_reorganize_low(
    /*====================*/
    ibool recovery,      /* in: TRUE if called in recovery:
                        locks should not be updated, i.e.,
                        there cannot exist locks on the
                        page, and a hash index should not be
                        dropped: it cannot exist */
    page_t *page,        /* in: page to be reorganized */
    dict_index_t *index, /* in: record descriptor */
    mtr_t *mtr)          /* in: mtr */
{
  page_t *new_page;
  ulint log_mode;
  ulint data_size1;
  ulint data_size2;
  ulint max_ins_size1;
  ulint max_ins_size2;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  ut_ad(!!page_is_comp(page) == index->table->comp);
  data_size1 = page_get_data_size(page);
  max_ins_size1 = page_get_max_insert_size_after_reorganize(page, 1);

  /* Write the log record */
  mlog_open_and_write_index(mtr, page, index, page_is_comp(page) ? MLOG_COMP_PAGE_REORGANIZE : MLOG_PAGE_REORGANIZE, 0);

  /* Turn logging off */
  log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);

  new_page = buf_frame_alloc();

  /* Copy the old page to temporary space */
  buf_frame_copy(new_page, page);

  if (!recovery)
  {
    btr_search_drop_page_hash_index(page);
  }

  /* Recreate the page: note that global data on page (possible
  segment headers, next page-field, etc.) is preserved intact */

  page_create(page, mtr, page_is_comp(page));
  buf_block_align(page)->check_index_page_at_flush = TRUE;

  /* Copy the records from the temporary space to the recreated page;
  do not copy the lock bits yet */

  page_copy_rec_list_end_no_locks(page, new_page, page_get_infimum_rec(new_page), index, mtr);
  /* Copy max trx id to recreated page */
  page_set_max_trx_id(page, page_get_max_trx_id(new_page));

  if (!recovery)
  {
    /* Update the record lock bitmaps */
    lock_move_reorganize_page(page, new_page);
  }

  data_size2 = page_get_data_size(page);
  max_ins_size2 = page_get_max_insert_size_after_reorganize(page, 1);

  if (data_size1 != data_size2 || max_ins_size1 != max_ins_size2)
  {
    buf_page_print(page);
    buf_page_print(new_page);
    fprintf(stderr,
            "InnoDB: Error: page old data size %lu new data size %lu\n"
            "InnoDB: Error: page old max ins size %lu new max ins size %lu\n"
            "InnoDB: Submit a detailed bug report to http://bugs.mysql.com\n",
            (unsigned long)data_size1, (unsigned long)data_size2, (unsigned long)max_ins_size1,
            (unsigned long)max_ins_size2);
  }

  buf_frame_free(new_page);

  /* Restore logging mode */
  mtr_set_log_mode(mtr, log_mode);
}

/*****************************************************************
Reorganizes an index page. */

void btr_page_reorganize(
    /*================*/
    page_t *page,        /* in: page to be reorganized */
    dict_index_t *index, /* in: record descriptor */
    mtr_t *mtr)          /* in: mtr */
{
  btr_page_reorganize_low(FALSE, page, index, mtr);
}

/***************************************************************
Parses a redo log record of reorganizing a page. */

byte *btr_parse_page_reorganize(
    /*======================*/
    /* out: end of log record or NULL */
    byte *ptr, /* in: buffer */
    byte *end_ptr __attribute__((unused)),
    /* in: buffer end */
    dict_index_t *index, /* in: record descriptor */
    page_t *page,        /* in: page or NULL */
    mtr_t *mtr)          /* in: mtr or NULL */
{
  ut_ad(ptr && end_ptr);

  /* The record is empty, except for the record initial part */

  if (page)
  {
    btr_page_reorganize_low(TRUE, page, index, mtr);
  }

  return (ptr);
}

/*****************************************************************
Empties an index page. */
static void btr_page_empty(
    /*===========*/
    page_t *page, /* in: page to be emptied */
    mtr_t *mtr)   /* in: mtr */
{
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  btr_search_drop_page_hash_index(page);

  /* Recreate the page: note that global data on page (possible
  segment headers, next page-field, etc.) is preserved intact */

  page_create(page, mtr, page_is_comp(page));
  buf_block_align(page)->check_index_page_at_flush = TRUE;
}

/*****************************************************************
Makes tree one level higher by splitting the root, and inserts
the tuple. It is assumed that mtr contains an x-latch on the tree.
NOTE that the operation of this function must always succeed,
we cannot reverse it: therefore enough free disk space must be
guaranteed to be available before this function is called. */

rec_t *btr_root_raise_and_insert(
    /*======================*/
    /* out: inserted record */
    btr_cur_t *cursor, /* in: cursor at which to insert: must be
                       on the root page; when the function returns,
                       the cursor is positioned on the predecessor
                       of the inserted record */
    dtuple_t *tuple,   /* in: tuple to insert */
    mtr_t *mtr)        /* in: mtr */
{
  dict_tree_t *tree;
  page_t *root;
  page_t *new_page;
  ulint new_page_no;
  rec_t *rec;
  mem_heap_t *heap;
  dtuple_t *node_ptr;
  ulint level;
  rec_t *node_ptr_rec;
  page_cur_t *page_cursor;

  root = btr_cur_get_page(cursor);
  tree = btr_cur_get_tree(cursor);

  ut_ad(dict_tree_get_page(tree) == buf_frame_get_page_no(root));
  ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
  ut_ad(mtr_memo_contains(mtr, buf_block_align(root), MTR_MEMO_PAGE_X_FIX));
  btr_search_drop_page_hash_index(root);

  /* Allocate a new page to the tree. Root splitting is done by first
  moving the root records to the new page, emptying the root, putting
  a node pointer to the new page, and then splitting the new page. */

  new_page = btr_page_alloc(tree, 0, FSP_NO_DIR, btr_page_get_level(root, mtr), mtr);

  btr_page_create(new_page, tree, mtr);

  level = btr_page_get_level(root, mtr);

  /* Set the levels of the new index page and root page */
  btr_page_set_level(new_page, level, mtr);
  btr_page_set_level(root, level + 1, mtr);

  /* Set the next node and previous node fields of new page */
  btr_page_set_next(new_page, FIL_NULL, mtr);
  btr_page_set_prev(new_page, FIL_NULL, mtr);

  /* Move the records from root to the new page */

  page_move_rec_list_end(new_page, root, page_get_infimum_rec(root), cursor->index, mtr);
  /* If this is a pessimistic insert which is actually done to
  perform a pessimistic update then we have stored the lock
  information of the record to be inserted on the infimum of the
  root page: we cannot discard the lock structs on the root page */

  lock_update_root_raise(new_page, root);

  /* Create a memory heap where the node pointer is stored */
  heap = mem_heap_create(100);

  rec = page_rec_get_next(page_get_infimum_rec(new_page));
  new_page_no = buf_frame_get_page_no(new_page);

  /* Build the node pointer (= node key and page address) for the
  child */

  node_ptr = dict_tree_build_node_ptr(tree, rec, new_page_no, heap, level);
  /* Reorganize the root to get free space */
  btr_page_reorganize(root, cursor->index, mtr);

  page_cursor = btr_cur_get_page_cur(cursor);

  /* Insert node pointer to the root */

  page_cur_set_before_first(root, page_cursor);

  node_ptr_rec = page_cur_tuple_insert(page_cursor, node_ptr, cursor->index, mtr);

  ut_ad(node_ptr_rec);

  /* The node pointer must be marked as the predefined minimum record,
  as there is no lower alphabetical limit to records in the leftmost
  node of a level: */

  btr_set_min_rec_mark(node_ptr_rec, page_is_comp(root), mtr);

  /* Free the memory heap */
  mem_heap_free(heap);

  /* We play safe and reset the free bits for the new page */

  /*	fprintf(stderr, "Root raise new page no %lu\n",
                                          buf_frame_get_page_no(new_page)); */

  ibuf_reset_free_bits(UT_LIST_GET_FIRST(tree->tree_indexes), new_page);
  /* Reposition the cursor to the child node */
  page_cur_search(new_page, cursor->index, tuple, PAGE_CUR_LE, page_cursor);

  /* Split the child and insert tuple */
  return (btr_page_split_and_insert(cursor, tuple, mtr));
}

/*****************************************************************
Decides if the page should be split at the convergence point of inserts
converging to the left. */

ibool btr_page_get_split_rec_to_left(
    /*===========================*/
    /* out: TRUE if split recommended */
    btr_cur_t *cursor, /* in: cursor at which to insert */
    rec_t **split_rec) /* out: if split recommended,
                    the first record on upper half page,
                    or NULL if tuple to be inserted should
                    be first */
{
  page_t *page;
  rec_t *insert_point;
  rec_t *infimum;

  page = btr_cur_get_page(cursor);
  insert_point = btr_cur_get_rec(cursor);

  if (page_header_get_ptr(page, PAGE_LAST_INSERT) == page_rec_get_next(insert_point))
  {
    infimum = page_get_infimum_rec(page);

    /* If the convergence is in the middle of a page, include also
    the record immediately before the new insert to the upper
    page. Otherwise, we could repeatedly move from page to page
    lots of records smaller than the convergence point. */

    if (infimum != insert_point && page_rec_get_next(infimum) != insert_point)
    {
      *split_rec = insert_point;
    }
    else
    {
      *split_rec = page_rec_get_next(insert_point);
    }

    return (TRUE);
  }

  return (FALSE);
}

/*****************************************************************
Decides if the page should be split at the convergence point of inserts
converging to the right. */

ibool btr_page_get_split_rec_to_right(
    /*============================*/
    /* out: TRUE if split recommended */
    btr_cur_t *cursor, /* in: cursor at which to insert */
    rec_t **split_rec) /* out: if split recommended,
                    the first record on upper half page,
                    or NULL if tuple to be inserted should
                    be first */
{
  page_t *page;
  rec_t *insert_point;

  page = btr_cur_get_page(cursor);
  insert_point = btr_cur_get_rec(cursor);

  /* We use eager heuristics: if the new insert would be right after
  the previous insert on the same page, we assume that there is a
  pattern of sequential inserts here. */

  if (UNIV_LIKELY(page_header_get_ptr(page, PAGE_LAST_INSERT) == insert_point))
  {
    rec_t *next_rec;

    next_rec = page_rec_get_next(insert_point);

    if (page_rec_is_supremum(next_rec))
    {
    split_at_new:
      /* Split at the new record to insert */
      *split_rec = NULL;
    }
    else
    {
      rec_t *next_next_rec = page_rec_get_next(next_rec);
      if (page_rec_is_supremum(next_next_rec))
      {
        goto split_at_new;
      }

      /* If there are >= 2 user records up from the insert
      point, split all but 1 off. We want to keep one because
      then sequential inserts can use the adaptive hash
      index, as they can do the necessary checks of the right
      search position just by looking at the records on this
      page. */

      *split_rec = next_next_rec;
    }

    return (TRUE);
  }

  return (FALSE);
}

/*****************************************************************
Calculates a split record such that the tuple will certainly fit on
its half-page when the split is performed. We assume in this function
only that the cursor page has at least one user record. */
static rec_t *btr_page_get_sure_split_rec(
    /*========================*/
    /* out: split record, or NULL if
    tuple will be the first record on
    upper half-page */
    btr_cur_t *cursor, /* in: cursor at which insert
                       should be made */
    dtuple_t *tuple)   /* in: tuple to insert */
{
  page_t *page;
  ulint insert_size;
  ulint free_space;
  ulint total_data;
  ulint total_n_recs;
  ulint total_space;
  ulint incl_data;
  rec_t *ins_rec;
  rec_t *rec;
  rec_t *next_rec;
  ulint n;
  mem_heap_t *heap;
  ulint *offsets;

  page = btr_cur_get_page(cursor);

  insert_size = rec_get_converted_size(cursor->index, tuple);
  free_space = page_get_free_space_of_empty(page_is_comp(page));

  /* free_space is now the free space of a created new page */

  total_data = page_get_data_size(page) + insert_size;
  total_n_recs = page_get_n_recs(page) + 1;
  ut_ad(total_n_recs >= 2);
  total_space = total_data + page_dir_calc_reserved_space(total_n_recs);

  n = 0;
  incl_data = 0;
  ins_rec = btr_cur_get_rec(cursor);
  rec = page_get_infimum_rec(page);

  heap = NULL;
  offsets = NULL;

  /* We start to include records to the left half, and when the
  space reserved by them exceeds half of total_space, then if
  the included records fit on the left page, they will be put there
  if something was left over also for the right page,
  otherwise the last included record will be the first on the right
  half page */

  for (;;)
  {
    /* Decide the next record to include */
    if (rec == ins_rec)
    {
      rec = NULL; /* NULL denotes that tuple is
                  now included */
    }
    else if (rec == NULL)
    {
      rec = page_rec_get_next(ins_rec);
    }
    else
    {
      rec = page_rec_get_next(rec);
    }

    if (rec == NULL)
    {
      /* Include tuple */
      incl_data += insert_size;
    }
    else
    {
      offsets = rec_get_offsets(rec, cursor->index, offsets, ULINT_UNDEFINED, &heap);
      incl_data += rec_offs_size(offsets);
    }

    n++;

    if (incl_data + page_dir_calc_reserved_space(n) >= total_space / 2)
    {
      if (incl_data + page_dir_calc_reserved_space(n) <= free_space)
      {
        /* The next record will be the first on
        the right half page if it is not the
        supremum record of page */

        if (rec == ins_rec)
        {
          rec = NULL;

          goto func_exit;
        }
        else if (rec == NULL)
        {
          next_rec = page_rec_get_next(ins_rec);
        }
        else
        {
          next_rec = page_rec_get_next(rec);
        }
        ut_ad(next_rec);
        if (!page_rec_is_supremum(next_rec))
        {
          rec = next_rec;
        }
      }

    func_exit:
      if (UNIV_LIKELY_NULL(heap))
      {
        mem_heap_free(heap);
      }
      return (rec);
    }
  }
}

/*****************************************************************
Returns TRUE if the insert fits on the appropriate half-page with the
chosen split_rec. */
static ibool btr_page_insert_fits(
    /*=================*/
    /* out: TRUE if fits */
    btr_cur_t *cursor,    /* in: cursor at which insert
                          should be made */
    rec_t *split_rec,     /* in: suggestion for first record
                          on upper half-page, or NULL if
                          tuple to be inserted should be first */
    const ulint *offsets, /* in: rec_get_offsets(
                          split_rec, cursor->index) */
    dtuple_t *tuple,      /* in: tuple to insert */
    mem_heap_t *heap)     /* in: temporary memory heap */
{
  page_t *page;
  ulint insert_size;
  ulint free_space;
  ulint total_data;
  ulint total_n_recs;
  rec_t *rec;
  rec_t *end_rec;
  ulint *offs;

  page = btr_cur_get_page(cursor);

  ut_ad(!split_rec == !offsets);
  ut_ad(!offsets || !page_is_comp(page) == !rec_offs_comp(offsets));
  ut_ad(!offsets || rec_offs_validate(split_rec, cursor->index, offsets));

  insert_size = rec_get_converted_size(cursor->index, tuple);
  free_space = page_get_free_space_of_empty(page_is_comp(page));

  /* free_space is now the free space of a created new page */

  total_data = page_get_data_size(page) + insert_size;
  total_n_recs = page_get_n_recs(page) + 1;

  /* We determine which records (from rec to end_rec, not including
  end_rec) will end up on the other half page from tuple when it is
  inserted. */

  if (split_rec == NULL)
  {
    rec = page_rec_get_next(page_get_infimum_rec(page));
    end_rec = page_rec_get_next(btr_cur_get_rec(cursor));
  }
  else if (cmp_dtuple_rec(tuple, split_rec, offsets) >= 0)
  {
    rec = page_rec_get_next(page_get_infimum_rec(page));
    end_rec = split_rec;
  }
  else
  {
    rec = split_rec;
    end_rec = page_get_supremum_rec(page);
  }

  if (total_data + page_dir_calc_reserved_space(total_n_recs) <= free_space)
  {
    /* Ok, there will be enough available space on the
    half page where the tuple is inserted */

    return (TRUE);
  }

  offs = NULL;

  while (rec != end_rec)
  {
    /* In this loop we calculate the amount of reserved
    space after rec is removed from page. */

    offs = rec_get_offsets(rec, cursor->index, offs, ULINT_UNDEFINED, &heap);

    total_data -= rec_offs_size(offs);
    total_n_recs--;

    if (total_data + page_dir_calc_reserved_space(total_n_recs) <= free_space)
    {
      /* Ok, there will be enough available space on the
      half page where the tuple is inserted */

      return (TRUE);
    }

    rec = page_rec_get_next(rec);
  }

  return (FALSE);
}

/***********************************************************
Inserts a data tuple to a tree on a non-leaf level. It is assumed
that mtr holds an x-latch on the tree. */

void btr_insert_on_non_leaf_level(
    /*=========================*/
    dict_tree_t *tree, /* in: tree */
    ulint level,       /* in: level, must be > 0 */
    dtuple_t *tuple,   /* in: the record to be inserted */
    mtr_t *mtr)        /* in: mtr */
{
  big_rec_t *dummy_big_rec;
  btr_cur_t cursor;
  ulint err;
  rec_t *rec;

  ut_ad(level > 0);

  /* In the following, choose just any index from the tree as the
  first parameter for btr_cur_search_to_nth_level. */

  btr_cur_search_to_nth_level(UT_LIST_GET_FIRST(tree->tree_indexes), level, tuple, PAGE_CUR_LE, BTR_CONT_MODIFY_TREE,
                              &cursor, 0, mtr);

  err = btr_cur_pessimistic_insert(BTR_NO_LOCKING_FLAG | BTR_KEEP_SYS_FLAG | BTR_NO_UNDO_LOG_FLAG, &cursor, tuple, &rec,
                                   &dummy_big_rec, NULL, mtr);
  ut_a(err == DB_SUCCESS);
}

/******************************************************************
Attaches the halves of an index page on the appropriate level in an
index tree. */
static void btr_attach_half_pages(
    /*==================*/
    dict_tree_t *tree, /* in: the index tree */
    page_t *page,      /* in: page to be split */
    rec_t *split_rec,  /* in: first record on upper
                       half page */
    page_t *new_page,  /* in: the new half page */
    ulint direction,   /* in: FSP_UP or FSP_DOWN */
    mtr_t *mtr)        /* in: mtr */
{
  ulint space;
  rec_t *node_ptr;
  page_t *prev_page;
  page_t *next_page;
  ulint prev_page_no;
  ulint next_page_no;
  ulint level;
  page_t *lower_page;
  page_t *upper_page;
  ulint lower_page_no;
  ulint upper_page_no;
  dtuple_t *node_ptr_upper;
  mem_heap_t *heap;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  ut_ad(mtr_memo_contains(mtr, buf_block_align(new_page), MTR_MEMO_PAGE_X_FIX));
  ut_a(page_is_comp(page) == page_is_comp(new_page));

  /* Create a memory heap where the data tuple is stored */
  heap = mem_heap_create(1024);

  /* Based on split direction, decide upper and lower pages */
  if (direction == FSP_DOWN)
  {
    lower_page_no = buf_frame_get_page_no(new_page);
    upper_page_no = buf_frame_get_page_no(page);
    lower_page = new_page;
    upper_page = page;

    /* Look from the tree for the node pointer to page */
    node_ptr = btr_page_get_father_node_ptr(tree, page, mtr);

    /* Replace the address of the old child node (= page) with the
    address of the new lower half */

    btr_node_ptr_set_child_page_no(
        node_ptr, rec_get_offsets(node_ptr, UT_LIST_GET_FIRST(tree->tree_indexes), NULL, ULINT_UNDEFINED, &heap),
        lower_page_no, mtr);
    mem_heap_empty(heap);
  }
  else
  {
    lower_page_no = buf_frame_get_page_no(page);
    upper_page_no = buf_frame_get_page_no(new_page);
    lower_page = page;
    upper_page = new_page;
  }

  /* Get the level of the split pages */
  level = btr_page_get_level(page, mtr);

  /* Build the node pointer (= node key and page address) for the upper
  half */

  node_ptr_upper = dict_tree_build_node_ptr(tree, split_rec, upper_page_no, heap, level);

  /* Insert it next to the pointer to the lower half. Note that this
  may generate recursion leading to a split on the higher level. */

  btr_insert_on_non_leaf_level(tree, level + 1, node_ptr_upper, mtr);

  /* Free the memory heap */
  mem_heap_free(heap);

  /* Get the previous and next pages of page */

  prev_page_no = btr_page_get_prev(page, mtr);
  next_page_no = btr_page_get_next(page, mtr);
  space = buf_frame_get_space_id(page);

  /* Update page links of the level */

  if (prev_page_no != FIL_NULL)
  {
    prev_page = btr_page_get(space, prev_page_no, RW_X_LATCH, mtr);
    ut_a(page_is_comp(prev_page) == page_is_comp(page));

    btr_page_set_next(prev_page, lower_page_no, mtr);
  }

  if (next_page_no != FIL_NULL)
  {
    next_page = btr_page_get(space, next_page_no, RW_X_LATCH, mtr);
    ut_a(page_is_comp(next_page) == page_is_comp(page));

    btr_page_set_prev(next_page, upper_page_no, mtr);
  }

  btr_page_set_prev(lower_page, prev_page_no, mtr);
  btr_page_set_next(lower_page, upper_page_no, mtr);
  btr_page_set_level(lower_page, level, mtr);

  btr_page_set_prev(upper_page, lower_page_no, mtr);
  btr_page_set_next(upper_page, next_page_no, mtr);
  btr_page_set_level(upper_page, level, mtr);
}

/*****************************************************************
Splits an index page to halves and inserts the tuple. It is assumed
that mtr holds an x-latch to the index tree. NOTE: the tree x-latch
is released within this function! NOTE that the operation of this
function must always succeed, we cannot reverse it: therefore
enough free disk space must be guaranteed to be available before
this function is called. */

rec_t *btr_page_split_and_insert(
    /*======================*/
    /* out: inserted record; NOTE: the tree
    x-latch is released! NOTE: 2 free disk
    pages must be available! */
    btr_cur_t *cursor, /* in: cursor at which to insert; when the
                       function returns, the cursor is positioned
                       on the predecessor of the inserted record */
    dtuple_t *tuple,   /* in: tuple to insert */
    mtr_t *mtr)        /* in: mtr */
{
  dict_tree_t *tree;
  page_t *page;
  ulint page_no;
  byte direction;
  ulint hint_page_no;
  page_t *new_page;
  rec_t *split_rec;
  page_t *left_page;
  page_t *right_page;
  page_t *insert_page;
  page_cur_t *page_cursor;
  rec_t *first_rec;
  byte *buf = 0; /* remove warning */
  rec_t *move_limit;
  ibool insert_will_fit;
  ulint n_iterations = 0;
  rec_t *rec;
  mem_heap_t *heap;
  ulint n_uniq;
  ulint *offsets;

  heap = mem_heap_create(1024);
  n_uniq = dict_index_get_n_unique_in_tree(cursor->index);
func_start:
  mem_heap_empty(heap);
  offsets = NULL;
  tree = btr_cur_get_tree(cursor);

  ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
#ifdef UNIV_SYNC_DEBUG
  ut_ad(rw_lock_own(dict_tree_get_lock(tree), RW_LOCK_EX));
#endif /* UNIV_SYNC_DEBUG */

  page = btr_cur_get_page(cursor);

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  ut_ad(page_get_n_recs(page) >= 2);

  page_no = buf_frame_get_page_no(page);

  /* 1. Decide the split record; split_rec == NULL means that the
  tuple to be inserted should be the first record on the upper
  half-page */

  if (n_iterations > 0)
  {
    direction = FSP_UP;
    hint_page_no = page_no + 1;
    split_rec = btr_page_get_sure_split_rec(cursor, tuple);
  }
  else if (btr_page_get_split_rec_to_right(cursor, &split_rec))
  {
    direction = FSP_UP;
    hint_page_no = page_no + 1;
  }
  else if (btr_page_get_split_rec_to_left(cursor, &split_rec))
  {
    direction = FSP_DOWN;
    hint_page_no = page_no - 1;
  }
  else
  {
    direction = FSP_UP;
    hint_page_no = page_no + 1;
    split_rec = page_get_middle_rec(page);
  }

  /* 2. Allocate a new page to the tree */
  new_page = btr_page_alloc(tree, hint_page_no, direction, btr_page_get_level(page, mtr), mtr);
  btr_page_create(new_page, tree, mtr);

  /* 3. Calculate the first record on the upper half-page, and the
  first record (move_limit) on original page which ends up on the
  upper half */

  if (split_rec != NULL)
  {
    first_rec = split_rec;
    move_limit = split_rec;
  }
  else
  {
    buf = mem_alloc(rec_get_converted_size(cursor->index, tuple));

    first_rec = rec_convert_dtuple_to_rec(buf, cursor->index, tuple);
    move_limit = page_rec_get_next(btr_cur_get_rec(cursor));
  }

  /* 4. Do first the modifications in the tree structure */

  btr_attach_half_pages(tree, page, first_rec, new_page, direction, mtr);

  if (split_rec == NULL)
  {
    mem_free(buf);
  }

  /* If the split is made on the leaf level and the insert will fit
  on the appropriate half-page, we may release the tree x-latch.
  We can then move the records after releasing the tree latch,
  thus reducing the tree latch contention. */

  if (split_rec)
  {
    offsets = rec_get_offsets(split_rec, cursor->index, offsets, n_uniq, &heap);

    insert_will_fit = btr_page_insert_fits(cursor, split_rec, offsets, tuple, heap);
  }
  else
  {
    insert_will_fit = btr_page_insert_fits(cursor, NULL, NULL, tuple, heap);
  }

  if (insert_will_fit && (btr_page_get_level(page, mtr) == 0))
  {
    mtr_memo_release(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK);
  }

  /* 5. Move then the records to the new page */
  if (direction == FSP_DOWN)
  {
    /*		fputs("Split left\n", stderr); */

    page_move_rec_list_start(new_page, page, move_limit, cursor->index, mtr);
    left_page = new_page;
    right_page = page;

    lock_update_split_left(right_page, left_page);
  }
  else
  {
    /*		fputs("Split right\n", stderr); */

    page_move_rec_list_end(new_page, page, move_limit, cursor->index, mtr);
    left_page = page;
    right_page = new_page;

    lock_update_split_right(right_page, left_page);
  }

  /* 6. The split and the tree modification is now completed. Decide the
  page where the tuple should be inserted */

  if (split_rec == NULL)
  {
    insert_page = right_page;
  }
  else
  {
    offsets = rec_get_offsets(first_rec, cursor->index, offsets, n_uniq, &heap);

    if (cmp_dtuple_rec(tuple, first_rec, offsets) >= 0)
    {
      insert_page = right_page;
    }
    else
    {
      insert_page = left_page;
    }
  }

  /* 7. Reposition the cursor for insert and try insertion */
  page_cursor = btr_cur_get_page_cur(cursor);

  page_cur_search(insert_page, cursor->index, tuple, PAGE_CUR_LE, page_cursor);

  rec = page_cur_tuple_insert(page_cursor, tuple, cursor->index, mtr);

  if (rec != NULL)
  {
    /* Insert fit on the page: update the free bits for the
    left and right pages in the same mtr */

    ibuf_update_free_bits_for_two_pages_low(cursor->index, left_page, right_page, mtr);
    /* fprintf(stderr, "Split and insert done %lu %lu\n",
                    buf_frame_get_page_no(left_page),
                    buf_frame_get_page_no(right_page)); */
    mem_heap_free(heap);
    return (rec);
  }

  /* 8. If insert did not fit, try page reorganization */

  btr_page_reorganize(insert_page, cursor->index, mtr);

  page_cur_search(insert_page, cursor->index, tuple, PAGE_CUR_LE, page_cursor);
  rec = page_cur_tuple_insert(page_cursor, tuple, cursor->index, mtr);

  if (rec == NULL)
  {
    /* The insert did not fit on the page: loop back to the
    start of the function for a new split */

    /* We play safe and reset the free bits for new_page */
    ibuf_reset_free_bits(cursor->index, new_page);

    /* fprintf(stderr, "Split second round %lu\n",
                            buf_frame_get_page_no(page)); */
    n_iterations++;
    ut_ad(n_iterations < 2);
    ut_ad(!insert_will_fit);

    goto func_start;
  }

  /* Insert fit on the page: update the free bits for the
  left and right pages in the same mtr */

  ibuf_update_free_bits_for_two_pages_low(cursor->index, left_page, right_page, mtr);
  /* fprintf(stderr, "Split and insert done %lu %lu\n",
                          buf_frame_get_page_no(left_page),
                          buf_frame_get_page_no(right_page)); */

  ut_ad(page_validate(left_page, UT_LIST_GET_FIRST(tree->tree_indexes)));
  ut_ad(page_validate(right_page, UT_LIST_GET_FIRST(tree->tree_indexes)));

  mem_heap_free(heap);
  return (rec);
}

/*****************************************************************
Removes a page from the level list of pages. */
static void btr_level_list_remove(
    /*==================*/
    dict_tree_t *tree __attribute__((unused)), /* in: index tree */
    page_t *page,                              /* in: page to remove */
    mtr_t *mtr)                                /* in: mtr */
{
  ulint space;
  ulint prev_page_no;
  page_t *prev_page;
  ulint next_page_no;
  page_t *next_page;

  ut_ad(tree && page && mtr);
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  /* Get the previous and next page numbers of page */

  prev_page_no = btr_page_get_prev(page, mtr);
  next_page_no = btr_page_get_next(page, mtr);
  space = buf_frame_get_space_id(page);

  /* Update page links of the level */

  if (prev_page_no != FIL_NULL)
  {
    prev_page = btr_page_get(space, prev_page_no, RW_X_LATCH, mtr);
    ut_a(page_is_comp(prev_page) == page_is_comp(page));

    btr_page_set_next(prev_page, next_page_no, mtr);
  }

  if (next_page_no != FIL_NULL)
  {
    next_page = btr_page_get(space, next_page_no, RW_X_LATCH, mtr);
    ut_a(page_is_comp(next_page) == page_is_comp(page));

    btr_page_set_prev(next_page, prev_page_no, mtr);
  }
}

/********************************************************************
Writes the redo log record for setting an index record as the predefined
minimum record. */
UNIV_INLINE
void btr_set_min_rec_mark_log(
    /*=====================*/
    rec_t *rec, /* in: record */
    ulint comp, /* nonzero=compact record format */
    mtr_t *mtr) /* in: mtr */
{
  mlog_write_initial_log_record(rec, comp ? MLOG_COMP_REC_MIN_MARK : MLOG_REC_MIN_MARK, mtr);

  /* Write rec offset as a 2-byte ulint */
  mlog_catenate_ulint(mtr, ut_align_offset(rec, UNIV_PAGE_SIZE), MLOG_2BYTES);
}

/********************************************************************
Parses the redo log record for setting an index record as the predefined
minimum record. */

byte *btr_parse_set_min_rec_mark(
    /*=======================*/
    /* out: end of log record or NULL */
    byte *ptr,     /* in: buffer */
    byte *end_ptr, /* in: buffer end */
    ulint comp,    /* in: nonzero=compact page format */
    page_t *page,  /* in: page or NULL */
    mtr_t *mtr)    /* in: mtr or NULL */
{
  rec_t *rec;

  if (end_ptr < ptr + 2)
  {
    return (NULL);
  }

  if (page)
  {
    ut_a(!page_is_comp(page) == !comp);

    rec = page + mach_read_from_2(ptr);

    btr_set_min_rec_mark(rec, comp, mtr);
  }

  return (ptr + 2);
}

/********************************************************************
Sets a record as the predefined minimum record. */

void btr_set_min_rec_mark(
    /*=================*/
    rec_t *rec, /* in: record */
    ulint comp, /* in: nonzero=compact page format */
    mtr_t *mtr) /* in: mtr */
{
  ulint info_bits;

  info_bits = rec_get_info_bits(rec, comp);

  rec_set_info_bits(rec, comp, info_bits | REC_INFO_MIN_REC_FLAG);

  btr_set_min_rec_mark_log(rec, comp, mtr);
}

/*****************************************************************
Deletes on the upper level the node pointer to a page. */

void btr_node_ptr_delete(
    /*================*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page whose node pointer is deleted */
    mtr_t *mtr)        /* in: mtr */
{
  rec_t *node_ptr;
  btr_cur_t cursor;
  ibool compressed;
  ulint err;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  /* Delete node pointer on father page */

  node_ptr = btr_page_get_father_node_ptr(tree, page, mtr);

  btr_cur_position(UT_LIST_GET_FIRST(tree->tree_indexes), node_ptr, &cursor);
  compressed = btr_cur_pessimistic_delete(&err, TRUE, &cursor, FALSE, mtr);
  ut_a(err == DB_SUCCESS);

  if (!compressed)
  {
    btr_cur_compress_if_useful(&cursor, mtr);
  }
}

/*****************************************************************
If page is the only on its level, this function moves its records to the
father page, thus reducing the tree height. */
static void btr_lift_page_up(
    /*=============*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page which is the only on its level;
                       must not be empty: use
                       btr_discard_only_page_on_level if the last
                       record from the page should be removed */
    mtr_t *mtr)        /* in: mtr */
{
  page_t *father_page;
  ulint page_level;
  dict_index_t *index;

  ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
  ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  father_page = buf_frame_align(btr_page_get_father_node_ptr(tree, page, mtr));

  page_level = btr_page_get_level(page, mtr);
  index = UT_LIST_GET_FIRST(tree->tree_indexes);

  btr_search_drop_page_hash_index(page);

  /* Make the father empty */
  btr_page_empty(father_page, mtr);

  /* Move records to the father */
  page_copy_rec_list_end(father_page, page, page_get_infimum_rec(page), index, mtr);
  lock_update_copy_and_discard(father_page, page);

  btr_page_set_level(father_page, page_level, mtr);

  /* Free the file page */
  btr_page_free(tree, page, mtr);

  /* We play safe and reset the free bits for the father */
  ibuf_reset_free_bits(index, father_page);
  ut_ad(page_validate(father_page, index));
  ut_ad(btr_check_node_ptr(tree, father_page, mtr));
}

/*****************************************************************
Tries to merge the page first to the left immediate brother if such a
brother exists, and the node pointers to the current page and to the brother
reside on the same page. If the left brother does not satisfy these
conditions, looks at the right brother. If the page is the only one on that
level lifts the records of the page to the father page, thus reducing the
tree height. It is assumed that mtr holds an x-latch on the tree and on the
page. If cursor is on the leaf level, mtr must also hold x-latches to the
brothers, if they exist. NOTE: it is assumed that the caller has reserved
enough free extents so that the compression will always succeed if done! */

void btr_compress(
    /*=========*/
    btr_cur_t *cursor, /* in: cursor on the page to merge or lift;
                       the page must not be empty: in record delete
                       use btr_discard_page if the page would become
                       empty */
    mtr_t *mtr)        /* in: mtr */
{
  dict_tree_t *tree;
  ulint space;
  ulint left_page_no;
  ulint right_page_no;
  page_t *merge_page;
  page_t *father_page;
  ibool is_left;
  page_t *page;
  rec_t *orig_pred;
  rec_t *orig_succ;
  rec_t *node_ptr;
  ulint data_size;
  ulint n_recs;
  ulint max_ins_size;
  ulint max_ins_size_reorg;
  ulint level;
  ulint comp;

  page = btr_cur_get_page(cursor);
  tree = btr_cur_get_tree(cursor);
  comp = page_is_comp(page);
  ut_a((ibool) !!comp == cursor->index->table->comp);

  ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  level = btr_page_get_level(page, mtr);
  space = dict_tree_get_space(tree);

  left_page_no = btr_page_get_prev(page, mtr);
  right_page_no = btr_page_get_next(page, mtr);

  /*	fprintf(stderr, "Merge left page %lu right %lu \n", left_page_no,
                                                          right_page_no); */

  node_ptr = btr_page_get_father_node_ptr(tree, page, mtr);
  ut_ad(!comp || rec_get_status(node_ptr) == REC_STATUS_NODE_PTR);
  father_page = buf_frame_align(node_ptr);
  ut_a(comp == page_is_comp(father_page));

  /* Decide the page to which we try to merge and which will inherit
  the locks */

  if (left_page_no != FIL_NULL)
  {
    is_left = TRUE;
    merge_page = btr_page_get(space, left_page_no, RW_X_LATCH, mtr);
  }
  else if (right_page_no != FIL_NULL)
  {
    is_left = FALSE;
    merge_page = btr_page_get(space, right_page_no, RW_X_LATCH, mtr);
  }
  else
  {
    /* The page is the only one on the level, lift the records
    to the father */
    btr_lift_page_up(tree, page, mtr);

    return;
  }

  n_recs = page_get_n_recs(page);
  data_size = page_get_data_size(page);
  ut_a(page_is_comp(merge_page) == comp);

  max_ins_size_reorg = page_get_max_insert_size_after_reorganize(merge_page, n_recs);
  if (data_size > max_ins_size_reorg)
  {
    /* No space for merge */

    return;
  }

  ut_ad(page_validate(merge_page, cursor->index));

  max_ins_size = page_get_max_insert_size(merge_page, n_recs);

  if (data_size > max_ins_size)
  {
    /* We have to reorganize merge_page */

    btr_page_reorganize(merge_page, cursor->index, mtr);

    max_ins_size = page_get_max_insert_size(merge_page, n_recs);

    ut_ad(page_validate(merge_page, cursor->index));
    ut_ad(page_get_max_insert_size(merge_page, n_recs) == max_ins_size_reorg);
  }

  if (data_size > max_ins_size)
  {
    /* Add fault tolerance, though this should never happen */

    return;
  }

  btr_search_drop_page_hash_index(page);

  /* Remove the page from the level list */
  btr_level_list_remove(tree, page, mtr);

  if (is_left)
  {
    btr_node_ptr_delete(tree, page, mtr);
  }
  else
  {
    mem_heap_t *heap = NULL;
    ulint offsets_[REC_OFFS_NORMAL_SIZE];
    *offsets_ = (sizeof offsets_) / sizeof *offsets_;
    /* Replace the address of the old child node (= page) with the
    address of the merge page to the right */

    btr_node_ptr_set_child_page_no(node_ptr, rec_get_offsets(node_ptr, cursor->index, offsets_, ULINT_UNDEFINED, &heap),
                                   right_page_no, mtr);
    if (UNIV_LIKELY_NULL(heap))
    {
      mem_heap_free(heap);
    }
    btr_node_ptr_delete(tree, merge_page, mtr);
  }

  /* Move records to the merge page */
  if (is_left)
  {
    orig_pred = page_rec_get_prev(page_get_supremum_rec(merge_page));
    page_copy_rec_list_start(merge_page, page, page_get_supremum_rec(page), cursor->index, mtr);

    lock_update_merge_left(merge_page, orig_pred, page);
  }
  else
  {
    orig_succ = page_rec_get_next(page_get_infimum_rec(merge_page));
    page_copy_rec_list_end(merge_page, page, page_get_infimum_rec(page), cursor->index, mtr);

    lock_update_merge_right(orig_succ, page);
  }

  /* We have added new records to merge_page: update its free bits */
  ibuf_update_free_bits_if_full(cursor->index, merge_page, UNIV_PAGE_SIZE, ULINT_UNDEFINED);

  ut_ad(page_validate(merge_page, cursor->index));

  /* Free the file page */
  btr_page_free(tree, page, mtr);

  ut_ad(btr_check_node_ptr(tree, merge_page, mtr));
}

/*****************************************************************
Discards a page that is the only page on its level. */
static void btr_discard_only_page_on_level(
    /*===========================*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: page which is the only on its level */
    mtr_t *mtr)        /* in: mtr */
{
  rec_t *node_ptr;
  page_t *father_page;
  ulint page_level;

  ut_ad(btr_page_get_prev(page, mtr) == FIL_NULL);
  ut_ad(btr_page_get_next(page, mtr) == FIL_NULL);
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  btr_search_drop_page_hash_index(page);

  node_ptr = btr_page_get_father_node_ptr(tree, page, mtr);
  father_page = buf_frame_align(node_ptr);

  page_level = btr_page_get_level(page, mtr);

  lock_update_discard(page_get_supremum_rec(father_page), page);

  btr_page_set_level(father_page, page_level, mtr);

  /* Free the file page */
  btr_page_free(tree, page, mtr);

  if (buf_frame_get_page_no(father_page) == dict_tree_get_page(tree))
  {
    /* The father is the root page */

    btr_page_empty(father_page, mtr);

    /* We play safe and reset the free bits for the father */
    ibuf_reset_free_bits(UT_LIST_GET_FIRST(tree->tree_indexes), father_page);
  }
  else
  {
    ut_ad(page_get_n_recs(father_page) == 1);

    btr_discard_only_page_on_level(tree, father_page, mtr);
  }
}

/*****************************************************************
Discards a page from a B-tree. This is used to remove the last record from
a B-tree page: the whole page must be removed at the same time. This cannot
be used for the root page, which is allowed to be empty. */

void btr_discard_page(
    /*=============*/
    btr_cur_t *cursor, /* in: cursor on the page to discard: not on
                       the root page */
    mtr_t *mtr)        /* in: mtr */
{
  dict_tree_t *tree;
  ulint space;
  ulint left_page_no;
  ulint right_page_no;
  page_t *merge_page;
  ibool is_left;
  page_t *page;
  rec_t *node_ptr;

  page = btr_cur_get_page(cursor);
  tree = btr_cur_get_tree(cursor);

  ut_ad(dict_tree_get_page(tree) != buf_frame_get_page_no(page));
  ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  space = dict_tree_get_space(tree);

  /* Decide the page which will inherit the locks */

  left_page_no = btr_page_get_prev(page, mtr);
  right_page_no = btr_page_get_next(page, mtr);

  if (left_page_no != FIL_NULL)
  {
    is_left = TRUE;
    merge_page = btr_page_get(space, left_page_no, RW_X_LATCH, mtr);
  }
  else if (right_page_no != FIL_NULL)
  {
    is_left = FALSE;
    merge_page = btr_page_get(space, right_page_no, RW_X_LATCH, mtr);
  }
  else
  {
    btr_discard_only_page_on_level(tree, page, mtr);

    return;
  }

  ut_a(page_is_comp(merge_page) == page_is_comp(page));
  btr_search_drop_page_hash_index(page);

  if (left_page_no == FIL_NULL && btr_page_get_level(page, mtr) > 0)
  {
    /* We have to mark the leftmost node pointer on the right
    side page as the predefined minimum record */

    node_ptr = page_rec_get_next(page_get_infimum_rec(merge_page));

    ut_ad(page_rec_is_user_rec(node_ptr));

    btr_set_min_rec_mark(node_ptr, page_is_comp(merge_page), mtr);
  }

  btr_node_ptr_delete(tree, page, mtr);

  /* Remove the page from the level list */
  btr_level_list_remove(tree, page, mtr);

  if (is_left)
  {
    lock_update_discard(page_get_supremum_rec(merge_page), page);
  }
  else
  {
    lock_update_discard(page_rec_get_next(page_get_infimum_rec(merge_page)), page);
  }

  /* Free the file page */
  btr_page_free(tree, page, mtr);

  ut_ad(btr_check_node_ptr(tree, merge_page, mtr));
}

#ifdef UNIV_BTR_PRINT
/*****************************************************************
Prints size info of a B-tree. */

void btr_print_size(
    /*===========*/
    dict_tree_t *tree) /* in: index tree */
{
  page_t *root;
  fseg_header_t *seg;
  mtr_t mtr;

  if (tree->type & DICT_IBUF)
  {
    fputs("Sorry, cannot print info of an ibuf tree: use ibuf functions\n", stderr);

    return;
  }

  mtr_start(&mtr);

  root = btr_root_get(tree, &mtr);

  seg = root + PAGE_HEADER + PAGE_BTR_SEG_TOP;

  fputs("INFO OF THE NON-LEAF PAGE SEGMENT\n", stderr);
  fseg_print(seg, &mtr);

  if (!(tree->type & DICT_UNIVERSAL))
  {
    seg = root + PAGE_HEADER + PAGE_BTR_SEG_LEAF;

    fputs("INFO OF THE LEAF PAGE SEGMENT\n", stderr);
    fseg_print(seg, &mtr);
  }

  mtr_commit(&mtr);
}

/****************************************************************
Prints recursively index tree pages. */
static void btr_print_recursive(
    /*================*/
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: index page */
    ulint width,       /* in: print this many entries from start
                       and end */
    mem_heap_t **heap, /* in/out: heap for rec_get_offsets() */
    ulint **offsets,   /* in/out: buffer for rec_get_offsets() */
    mtr_t *mtr)        /* in: mtr */
{
  page_cur_t cursor;
  ulint n_recs;
  ulint i = 0;
  mtr_t mtr2;
  rec_t *node_ptr;
  page_t *child;
  dict_index_t *index;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  fprintf(stderr, "NODE ON LEVEL %lu page number %lu\n", (ulong)btr_page_get_level(page, mtr),
          (ulong)buf_frame_get_page_no(page));

  index = UT_LIST_GET_FIRST(tree->tree_indexes);
  page_print(page, index, width, width);

  n_recs = page_get_n_recs(page);

  page_cur_set_before_first(page, &cursor);
  page_cur_move_to_next(&cursor);

  while (!page_cur_is_after_last(&cursor))
  {
    if (0 == btr_page_get_level(page, mtr))
    {
      /* If this is the leaf level, do nothing */
    }
    else if ((i <= width) || (i >= n_recs - width))
    {
      mtr_start(&mtr2);

      node_ptr = page_cur_get_rec(&cursor);

      *offsets = rec_get_offsets(node_ptr, index, *offsets, ULINT_UNDEFINED, heap);
      child = btr_node_ptr_get_child(node_ptr, *offsets, &mtr2);
      btr_print_recursive(tree, child, width, heap, offsets, &mtr2);
      mtr_commit(&mtr2);
    }

    page_cur_move_to_next(&cursor);
    i++;
  }
}

/******************************************************************
Prints directories and other info of all nodes in the tree. */

void btr_print_tree(
    /*===========*/
    dict_tree_t *tree, /* in: tree */
    ulint width)       /* in: print this many entries from start
                       and end */
{
  mtr_t mtr;
  page_t *root;
  mem_heap_t *heap = NULL;
  ulint offsets_[REC_OFFS_NORMAL_SIZE];
  ulint *offsets = offsets_;
  *offsets_ = (sizeof offsets_) / sizeof *offsets_;

  fputs(
      "--------------------------\n"
      "INDEX TREE PRINT\n",
      stderr);

  mtr_start(&mtr);

  root = btr_root_get(tree, &mtr);

  btr_print_recursive(tree, root, width, &heap, &offsets, &mtr);
  if (UNIV_LIKELY_NULL(heap))
  {
    mem_heap_free(heap);
  }

  mtr_commit(&mtr);

  btr_validate_tree(tree, NULL);
}
#endif /* UNIV_BTR_PRINT */

/****************************************************************
Checks that the node pointer to a page is appropriate. */

ibool btr_check_node_ptr(
    /*===============*/
    /* out: TRUE */
    dict_tree_t *tree, /* in: index tree */
    page_t *page,      /* in: index page */
    mtr_t *mtr)        /* in: mtr */
{
  mem_heap_t *heap;
  rec_t *node_ptr;
  dtuple_t *node_ptr_tuple;

  ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
  if (dict_tree_get_page(tree) == buf_frame_get_page_no(page))
  {
    return (TRUE);
  }

  node_ptr = btr_page_get_father_node_ptr(tree, page, mtr);

  if (btr_page_get_level(page, mtr) == 0)
  {
    return (TRUE);
  }

  heap = mem_heap_create(256);

  node_ptr_tuple = dict_tree_build_node_ptr(tree, page_rec_get_next(page_get_infimum_rec(page)), 0, heap,
                                            btr_page_get_level(page, mtr));

  ut_a(cmp_dtuple_rec(node_ptr_tuple, node_ptr,
                      rec_get_offsets(node_ptr, dict_tree_find_index(tree, node_ptr), NULL, ULINT_UNDEFINED, &heap)) ==
       0);

  mem_heap_free(heap);

  return (TRUE);
}

/****************************************************************
Display identification information for a record. */
static void btr_index_rec_validate_report(
    /*==========================*/
    page_t *page,        /* in: index page */
    rec_t *rec,          /* in: index record */
    dict_index_t *index) /* in: index */
{
  fputs("InnoDB: Record in ", stderr);
  dict_index_name_print(stderr, NULL, index);
  fprintf(stderr, ", page %lu, at offset %lu\n", buf_frame_get_page_no(page), (ulint)(rec - page));
}

/****************************************************************
Checks the size and number of fields in a record based on the definition of
the index. */

ibool btr_index_rec_validate(
    /*====================*/
    /* out: TRUE if ok */
    rec_t *rec,          /* in: index record */
    dict_index_t *index, /* in: index */
    ibool dump_on_error) /* in: TRUE if the function
                         should print hex dump of record
                         and page on error */
{
  ulint len;
  ulint n;
  ulint i;
  page_t *page;
  mem_heap_t *heap = NULL;
  ulint offsets_[REC_OFFS_NORMAL_SIZE];
  ulint *offsets = offsets_;
  *offsets_ = (sizeof offsets_) / sizeof *offsets_;

  page = buf_frame_align(rec);

  if (UNIV_UNLIKELY(index->type & DICT_UNIVERSAL))
  {
    /* The insert buffer index tree can contain records from any
    other index: we cannot check the number of fields or
    their length */

    return (TRUE);
  }

  if (UNIV_UNLIKELY((ibool) !!page_is_comp(page) != index->table->comp))
  {
    btr_index_rec_validate_report(page, rec, index);
    fprintf(stderr, "InnoDB: compact flag=%lu, should be %lu\n", (ulong) !!page_is_comp(page),
            (ulong)index->table->comp);
    return (FALSE);
  }

  n = dict_index_get_n_fields(index);

  if (!page_is_comp(page) && UNIV_UNLIKELY(rec_get_n_fields_old(rec) != n))
  {
    btr_index_rec_validate_report(page, rec, index);
    fprintf(stderr, "InnoDB: has %lu fields, should have %lu\n", (ulong)rec_get_n_fields_old(rec), (ulong)n);

    if (dump_on_error)
    {
      buf_page_print(page);

      fputs("InnoDB: corrupt record ", stderr);
      rec_print_old(stderr, rec);
      putc('\n', stderr);
    }
    return (FALSE);
  }

  offsets = rec_get_offsets(rec, index, offsets, ULINT_UNDEFINED, &heap);

  for (i = 0; i < n; i++)
  {
    dtype_t *type = dict_index_get_nth_type(index, i);
    ulint fixed_size = dtype_get_fixed_size(type);

    rec_get_nth_field(rec, offsets, i, &len);

    /* Note that prefix indexes are not fixed size even when
    their type is CHAR. */

    if ((dict_index_get_nth_field(index, i)->prefix_len == 0 && len != UNIV_SQL_NULL && fixed_size &&
         len != fixed_size) ||
        (dict_index_get_nth_field(index, i)->prefix_len > 0 && len != UNIV_SQL_NULL &&
         len > dict_index_get_nth_field(index, i)->prefix_len))
    {
      btr_index_rec_validate_report(page, rec, index);
      fprintf(stderr, "InnoDB: field %lu len is %lu, should be %lu\n", (ulong)i, (ulong)len,
              (ulong)dtype_get_fixed_size(type));

      if (dump_on_error)
      {
        buf_page_print(page);

        fputs("InnoDB: corrupt record ", stderr);
        rec_print_new(stderr, rec, offsets);
        putc('\n', stderr);
      }
      if (UNIV_LIKELY_NULL(heap))
      {
        mem_heap_free(heap);
      }
      return (FALSE);
    }
  }

  if (UNIV_LIKELY_NULL(heap))
  {
    mem_heap_free(heap);
  }
  return (TRUE);
}

/****************************************************************
Checks the size and number of fields in records based on the definition of
the index. */
static ibool btr_index_page_validate(
    /*====================*/
    /* out: TRUE if ok */
    page_t *page,        /* in: index page */
    dict_index_t *index) /* in: index */
{
  page_cur_t cur;
  ibool ret = TRUE;

  page_cur_set_before_first(page, &cur);
  page_cur_move_to_next(&cur);

  for (;;)
  {
    if (page_cur_is_after_last(&cur))
    {
      break;
    }

    if (!btr_index_rec_validate(cur.rec, index, TRUE))
    {
      return (FALSE);
    }

    page_cur_move_to_next(&cur);
  }

  return (ret);
}

/****************************************************************
Report an error on one page of an index tree. */
static void btr_validate_report1(
    /* out: TRUE if ok */
    dict_index_t *index, /* in: index */
    ulint level,         /* in: B-tree level */
    page_t *page)        /* in: index page */
{
  fprintf(stderr, "InnoDB: Error in page %lu of ", buf_frame_get_page_no(page));
  dict_index_name_print(stderr, NULL, index);
  if (level)
  {
    fprintf(stderr, ", index tree level %lu", level);
  }
  putc('\n', stderr);
}

/****************************************************************
Report an error on two pages of an index tree. */
static void btr_validate_report2(
    /* out: TRUE if ok */
    dict_index_t *index, /* in: index */
    ulint level,         /* in: B-tree level */
    page_t *page1,       /* in: first index page */
    page_t *page2)       /* in: second index page */
{
  fprintf(stderr, "InnoDB: Error in pages %lu and %lu of ", buf_frame_get_page_no(page1), buf_frame_get_page_no(page2));
  dict_index_name_print(stderr, NULL, index);
  if (level)
  {
    fprintf(stderr, ", index tree level %lu", level);
  }
  putc('\n', stderr);
}

/****************************************************************
Validates index tree level. */
static ibool btr_validate_level(
    /*===============*/
    /* out: TRUE if ok */
    dict_tree_t *tree, /* in: index tree */
    trx_t *trx,        /* in: transaction or NULL */
    ulint level)       /* in: level number */
{
  ulint space;
  page_t *page;
  page_t *right_page = 0; /* remove warning */
  page_t *father_page;
  page_t *right_father_page;
  rec_t *node_ptr;
  rec_t *right_node_ptr;
  rec_t *rec;
  ulint right_page_no;
  ulint left_page_no;
  page_cur_t cursor;
  dtuple_t *node_ptr_tuple;
  ibool ret = TRUE;
  dict_index_t *index;
  mtr_t mtr;
  mem_heap_t *heap = mem_heap_create(256);
  ulint *offsets = NULL;
  ulint *offsets2 = NULL;

  mtr_start(&mtr);

  mtr_x_lock(dict_tree_get_lock(tree), &mtr);

  page = btr_root_get(tree, &mtr);

  space = buf_frame_get_space_id(page);

  index = UT_LIST_GET_FIRST(tree->tree_indexes);

  while (level != btr_page_get_level(page, &mtr))
  {
    ut_a(btr_page_get_level(page, &mtr) > 0);

    page_cur_set_before_first(page, &cursor);
    page_cur_move_to_next(&cursor);

    node_ptr = page_cur_get_rec(&cursor);
    offsets = rec_get_offsets(node_ptr, index, offsets, ULINT_UNDEFINED, &heap);
    page = btr_node_ptr_get_child(node_ptr, offsets, &mtr);
  }

  /* Now we are on the desired level. Loop through the pages on that
  level. */
loop:
  if (trx_is_interrupted(trx))
  {
    mtr_commit(&mtr);
    mem_heap_free(heap);
    return (ret);
  }
  mem_heap_empty(heap);
  offsets = offsets2 = NULL;
  mtr_x_lock(dict_tree_get_lock(tree), &mtr);

  /* Check ordering etc. of records */

  if (!page_validate(page, index))
  {
    btr_validate_report1(index, level, page);

    ret = FALSE;
  }
  else if (level == 0)
  {
    /* We are on level 0. Check that the records have the right
    number of fields, and field lengths are right. */

    if (!btr_index_page_validate(page, index))
    {
      ret = FALSE;
    }
  }

  ut_a(btr_page_get_level(page, &mtr) == level);

  right_page_no = btr_page_get_next(page, &mtr);
  left_page_no = btr_page_get_prev(page, &mtr);

  ut_a((page_get_n_recs(page) > 0) || ((level == 0) && (buf_frame_get_page_no(page) == dict_tree_get_page(tree))));

  if (right_page_no != FIL_NULL)
  {
    rec_t *right_rec;
    right_page = btr_page_get(space, right_page_no, RW_X_LATCH, &mtr);
    ut_a(page_is_comp(right_page) == page_is_comp(page));
    rec = page_rec_get_prev(page_get_supremum_rec(page));
    right_rec = page_rec_get_next(page_get_infimum_rec(right_page));
    offsets = rec_get_offsets(rec, index, offsets, ULINT_UNDEFINED, &heap);
    offsets2 = rec_get_offsets(right_rec, index, offsets2, ULINT_UNDEFINED, &heap);
    if (cmp_rec_rec(rec, right_rec, offsets, offsets2, index) >= 0)
    {
      btr_validate_report2(index, level, page, right_page);

      fputs(
          "InnoDB: records in wrong order"
          " on adjacent pages\n",
          stderr);

      buf_page_print(page);
      buf_page_print(right_page);

      fputs("InnoDB: record ", stderr);
      rec = page_rec_get_prev(page_get_supremum_rec(page));
      rec_print(stderr, rec, index);
      putc('\n', stderr);
      fputs("InnoDB: record ", stderr);
      rec = page_rec_get_next(page_get_infimum_rec(right_page));
      rec_print(stderr, rec, index);
      putc('\n', stderr);

      ret = FALSE;
    }
  }

  if (level > 0 && left_page_no == FIL_NULL)
  {
    ut_a(REC_INFO_MIN_REC_FLAG & rec_get_info_bits(page_rec_get_next(page_get_infimum_rec(page)), page_is_comp(page)));
  }

  if (buf_frame_get_page_no(page) != dict_tree_get_page(tree))
  {
    /* Check father node pointers */

    node_ptr = btr_page_get_father_node_ptr(tree, page, &mtr);
    father_page = buf_frame_align(node_ptr);
    offsets = rec_get_offsets(node_ptr, index, offsets, ULINT_UNDEFINED, &heap);

    if (btr_node_ptr_get_child_page_no(node_ptr, offsets) != buf_frame_get_page_no(page) ||
        node_ptr != btr_page_get_father_for_rec(tree, page, page_rec_get_prev(page_get_supremum_rec(page)), &mtr))
    {
      btr_validate_report1(index, level, page);

      fputs("InnoDB: node pointer to the page is wrong\n", stderr);

      buf_page_print(father_page);
      buf_page_print(page);

      fputs("InnoDB: node ptr ", stderr);
      rec_print_new(stderr, node_ptr, offsets);

      fprintf(stderr,
              "\n"
              "InnoDB: node ptr child page n:o %lu\n",
              (unsigned long)btr_node_ptr_get_child_page_no(node_ptr, offsets));

      fputs("InnoDB: record on page ", stderr);
      rec = btr_page_get_father_for_rec(tree, page, page_rec_get_prev(page_get_supremum_rec(page)), &mtr);
      rec_print(stderr, rec, index);
      putc('\n', stderr);
      ret = FALSE;

      goto node_ptr_fails;
    }

    if (btr_page_get_level(page, &mtr) > 0)
    {
      offsets = rec_get_offsets(node_ptr, index, offsets, ULINT_UNDEFINED, &heap);

      node_ptr_tuple = dict_tree_build_node_ptr(tree, page_rec_get_next(page_get_infimum_rec(page)), 0, heap,
                                                btr_page_get_level(page, &mtr));

      if (cmp_dtuple_rec(node_ptr_tuple, node_ptr, offsets))
      {
        rec_t *first_rec = page_rec_get_next(page_get_infimum_rec(page));

        btr_validate_report1(index, level, page);

        buf_page_print(father_page);
        buf_page_print(page);

        fputs(
            "InnoDB: Error: node ptrs differ"
            " on levels > 0\n"
            "InnoDB: node ptr ",
            stderr);
        rec_print_new(stderr, node_ptr, offsets);
        fputs("InnoDB: first rec ", stderr);
        rec_print(stderr, first_rec, index);
        putc('\n', stderr);
        ret = FALSE;

        goto node_ptr_fails;
      }
    }

    if (left_page_no == FIL_NULL)
    {
      ut_a(node_ptr == page_rec_get_next(page_get_infimum_rec(father_page)));
      ut_a(btr_page_get_prev(father_page, &mtr) == FIL_NULL);
    }

    if (right_page_no == FIL_NULL)
    {
      ut_a(node_ptr == page_rec_get_prev(page_get_supremum_rec(father_page)));
      ut_a(btr_page_get_next(father_page, &mtr) == FIL_NULL);
    }

    if (right_page_no != FIL_NULL)
    {
      right_node_ptr = btr_page_get_father_node_ptr(tree, right_page, &mtr);
      if (page_rec_get_next(node_ptr) != page_get_supremum_rec(father_page))
      {
        if (right_node_ptr != page_rec_get_next(node_ptr))
        {
          ret = FALSE;
          fputs("InnoDB: node pointer to the right page is wrong\n", stderr);

          btr_validate_report1(index, level, page);

          buf_page_print(father_page);
          buf_page_print(page);
          buf_page_print(right_page);
        }
      }
      else
      {
        right_father_page = buf_frame_align(right_node_ptr);

        if (right_node_ptr != page_rec_get_next(page_get_infimum_rec(right_father_page)))
        {
          ret = FALSE;
          fputs("InnoDB: node pointer 2 to the right page is wrong\n", stderr);

          btr_validate_report1(index, level, page);

          buf_page_print(father_page);
          buf_page_print(right_father_page);
          buf_page_print(page);
          buf_page_print(right_page);
        }

        if (buf_frame_get_page_no(right_father_page) != btr_page_get_next(father_page, &mtr))
        {
          ret = FALSE;
          fputs("InnoDB: node pointer 3 to the right page is wrong\n", stderr);

          btr_validate_report1(index, level, page);

          buf_page_print(father_page);
          buf_page_print(right_father_page);
          buf_page_print(page);
          buf_page_print(right_page);
        }
      }
    }
  }

node_ptr_fails:
  mtr_commit(&mtr);

  if (right_page_no != FIL_NULL)
  {
    ulint comp = page_is_comp(page);
    mtr_start(&mtr);

    page = btr_page_get(space, right_page_no, RW_X_LATCH, &mtr);
    ut_a(page_is_comp(page) == comp);

    goto loop;
  }

  mem_heap_free(heap);
  return (ret);
}

/******************************************************************
Checks the consistency of an index tree. */

ibool btr_validate_tree(
    /*==============*/
    /* out: TRUE if ok */
    dict_tree_t *tree, /* in: tree */
    trx_t *trx)        /* in: transaction or NULL */
{
  mtr_t mtr;
  page_t *root;
  ulint i;
  ulint n;

  mtr_start(&mtr);
  mtr_x_lock(dict_tree_get_lock(tree), &mtr);

  root = btr_root_get(tree, &mtr);
  n = btr_page_get_level(root, &mtr);

  for (i = 0; i <= n && !trx_is_interrupted(trx); i++)
  {
    if (!btr_validate_level(tree, trx, n - i))
    {
      mtr_commit(&mtr);

      return (FALSE);
    }
  }

  mtr_commit(&mtr);

  return (TRUE);
}
